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laurb9 / StepperDriver

Arduino library for A4988, DRV8825, DRV8834, DRV8880 and generic two-pin (DIR/STEP) stepper motor drivers
MIT License
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Refuses to move high number of steps #96

Closed joymonkey closed 4 years ago

joymonkey commented 4 years ago

Describe the bug I'm having trouble telling my stepper to move a large amount of steps. This sketch successfully moves the motor 22934 steps, but when it is told to move 45868 steps, it will only move 19668 steps (checked using stepper.getStepsCompleted(), but I can also visually tell that the steps were not right).

To Reproduce https://gist.github.com/joymonkey/b95d479af7c2375a7479c3a6775653e7

Expected behavior Motor should move 45868 steps.

Platform Setup (please complete the following information):

Additional context Add any other context about the problem here.

joymonkey commented 4 years ago

Tested with full steps and confirm same behavior. Swapped out my 400-steps-per-rotation stepper motor for a more standard 200-steps-per-rotation motor and still seeing the same behavior. Also did some more tests... When commanded to move 32767 steps, it moves appropriately. When commanded to move 32768 steps, it refuses to move at all. When commanded to move 32769 steps or higher, it moves an incorrect number of steps.

laurb9 commented 4 years ago

Thank you for providing the details and the sample code. The number seems to indicate an issue with 16-bit signed math as you probably surmised, but we use long even on 8-bit platform... will take a look

joymonkey commented 4 years ago

I replaced the Arduino Nano Every with a knockoff Arduino Nano (common version with old bootloader), and this problem does not seem to persist. So it seems to be a problem particular to the Arduino Nano Every.

laurb9 commented 4 years ago

I was unable to reproduce the problem with an Arduino Uno either. I don't have any megaAVR boards unfortunately.

In Arduino the Every board has an option for 328 register emulation, is there a difference when enabling it ?

laurb9 commented 4 years ago

Hmm, I have a suspicion. Can you please add this to the test sketch and let me know if it prints the expected value or not ?

  long v = 32768;
  Serial.println(abs(v));
joymonkey commented 4 years ago

Hmm, I have a suspicion. Can you please add this to the test sketch and let me know if it prints the expected value or not ?

  long v = 32768;
  Serial.println(abs(v));

It prints the value as -32768 (negative)

laurb9 commented 4 years ago

Thank you for confirming, I will be creating 1.3.1 to hopefully address this